Vibrator driven by pressurized fluid

ABSTRACT

A vibrator is provided having an eccentric member enclosed in a housing and arranged to be set in motion in an eccentric and vibration-inducing rolling movement inside the housing, the eccentric member and the housing each being provided with intermeshing screw threads, the number of starts of the threads on the interior of the housing being one more than the number of starts in the threads on the exterior of the eccentric member.

Waited States Patent [1 1 Fransson et a1.

[ VIBRATOR DRIVEN BY PRESSURIZED FLUID [75] Inventors: Johnny Fransson, Akersberga;

Henrik Holmlund, Jakobsberg; Erik Kareby, Enskede, all of Sweden [73] Assignee: A B Vibra-Verken, Solna, Sweden [22] Filed: June 10, 1971 [21] Appl. No.: 151,669

[52] US. Cl 259/1 R, 259/DIG 43, 418/48 [51] Int. Cl B011 11/00 [58] Field of Search 259/1 R, DIG. 43,

[56] References Cited UNITED STATES PATENTS Moineau 418/48 Moineau 418/48 [451 July 17, 1973 3,296,874 1/1967 Wyczalek 259/1 R X 3,162,426 12/1964 Fontaine 259/D1G. 43

FOREIGN PATENTS OR APPLICATIONS 1,367,262 6/1964 France 418/48 425,447 3/1935 Great Britain 418/48 Primary ExaminerJohn Petrakes Assistant Examiner A1an I. Cantor Attorney-Janes & Chapman [57] ABSTRACT A vibrator is provided having an eccentric member onclosed in a housing and arranged to be set in motion in an eccentric and vibration-inducing rolling movement inside the housing, the eccentric member and the housing each being provided with intermeshing screw threads, the number of starts of the threads on the interior of the housing being one more than the number of starts in the threads on the exterior of the eccentric member.

10 Claims, 3 Drawing Figures 1 VIBRATOR DRIVEN BY PRESSURIZED FLUID One type of industrial vibrator useful for compacting concrete and similar materials comprises an eccentric member enclosed in a housing and arranged to move in an eccentric and vibration-inducing rolling movement inside the housing under the influence of the static pressure of the pressurized fluid passing through the vibrator. The pressurized fluid usually used is air. A valve is located across the pressurized fluid flow path, and controlled by the eccentric member during its rolling motion, in such a manner that the valve is automatically caused to open and close the inlet passage for the air flowing through the vibrator, and by this means create a pulsating air flow, with the necessary static pressure to induce the eccentric and vibration-inducing rolling movement of the eccentric member.

The difficulty with this type of device is that the valve is exposed to wear, due to the movement of the eccentric member, and dust and impurities may enter be-' tween the sliding or bearing surfaces of the valve, causing faulty operation. In addition, the valve is a moving part, which always presents the possibility of failure, as well as manufacturing and assembly difficulties.

Compressed air vibrators in which the dynamic energy of the air is employed as the motive force for the eccentric member, omitting the valve, have been proposed. However, such vibrators require a higher air flow and a higher air flow velocity to the vibrator than the valve-controlled static pressure type, in order to obtain a comparable performance.

In accordance with the instant invention, a vibrator having an eccentric member enclosed in a housing is provided which does not possess nor require a valve, but which nonetheless is operated by static pressure. The effect of the valve is obtained by the construction of the eccentric member and the housing within which it is disposed.

The vibrator of the invention comprises, in combination, a tubular housing, preferably a hollow cylinder, within which a tube or cylinder of smaller diameter is fitted, with one of the cylinders, usually the inner cylinder, being rotatable with respect to the other. The cylinder of smaller diameter is provided with screw threads on its outer periphery, and the cylindrical housing is provided with screw threads on its inner periphery, the number of starts of the threads on the interior of the cylindrical housing being one more than the number of starts of the threads on the exterior of the internal cylinder, and the threads of the internal cylinder engaging the threads on the inside of the cylindrical housing.

The threads on the internal cylinder are easily machined. However, the threading of the bore of the cylindrical housing may present manufacturing problems, especially when the cylinders are long, and have a relatively small diameter. It is accordingly advantageous to form these internal threads not in the housing but in cylindrical bushings which fit within the housing. One or more of such bushings can be provided, but each bushing should have a minimum total length equal to one pitch of the threads, in order to ensure that the pressurized medium is conducted along and not across the threads, and thus apply its static pressure to the threads.

Moreover, the bushings are large enough so that their largest bore is one height of thread greater than the outside diameter of the internal cylinder. The number of starts of the screw threads in the bushings is one more than the number of starts of the screw threads on the periphery of the internal cylinder. The bushings are designed to be inserted in the vibrator housing axially, in relation to each other, and enclosing the threaded section of the internal cylinder. The bushings can be fitted within the housing in a press fit, and they can also be bonded to the housing by soldering, brazing, or welding, or by a bonding agent.

Normally, the vibrator and its component parts are made of hardened steel. It is also possible to fabricate the bushings from a material which is more easily machined than the remainder of the vibrator, thus facilitating the forming of the internal threads. Wear on the bushings can then be avoided by providing the internal cylinder or rotor with special tracks which match similar tracks provided on the inside of the housing. These tracks are designed to carry the centrifugal force generated by the rotor or cylinder during its eccentric rolling movement, thus taking up the load which would otherwise be carried by the threaded sections of the rotor and the housing, and minimizing wear between the threads.

If the bushings are made in relatively small lengths, the machining of the internal threads therein is appreciably simplified.

If tracks are provided, and the centrifugal force generated by the rotor is absorbed by the tracks, the material of the bushings can be relatively soft, compared to the material of the remiander of the vibrator. It is then possible to fabricate the bushings of plastic, or similar easily machineable or moldable material. It is, for example, possible to mold a plastic bushing with the screw threads on the intemal-periphery, using plastic materials such as Teflon, nylon, polystyrene, polycarbonates, and polyester resins.

A preferred embodiment of the invention is shown in the drawings in which:

FIG. 1 represents a longitudinal section through a preferred embodiment of the invention, designed to be driven by compressed air, and intended for the compaction of concrete; and

FIG. 2 is a cross-section on asomewhat larger scale of the vibrator shown in FIG. 1, taken along the lines 2-2 in FIG. 1, and looking in the direction of the arrows; FIG. 3 is a cross-section on a somewhat larger scale of the vibrator shown in FIG. 1 taken along the lines 3-3 in FIG. 1 and looking in the direction of the arrows.

The vibrator shown in FIGS. 1, 2 and 3 comprises a housing 1 in which is fitted the rotor 2, the housing representing the external cylinder and the rotor representing the eccentric internal cylinder of smaller diameter. Three bushings 4, 4' and 4" fit snugly within the housing 1 in a press fit, and abut one another axially. Each bushing has five starts of internal threads 3 on its interior periphery. The rotor 2 is provided with four starts of threads 5 on its external periphery, and the threads 5 engage the threads 3 on the bushings 4.

Abutting the end bushings 4 and 4" are plain tracks 7 and 7', respectively. Each track has a recess 15 at its exterior end face, abutting the bushing, and in the recess is fitted an O-ring seal 16, to prevent fluid leakage therebetween. Each end of the rotor 2 beyond the threads 5 is provided with a plain cylindrical section 6,

6', these sections being in contact with the tracks 7, 7',

respectively, on the inside of the housing.

The housing 1 is open at one end 17, while the other end is closed by an end piece 12, bolted to the housing.

The end piece 12 constitutes a flat cap adapting the vibrator for the compaction of concrete. The end piece 12 has an internal recess 18, smaller in diameter than the internal bore 19 of the housing 1, and thus providing a ledge against which the track 7 may rest. The tracks 7 and 7' and the bushings 4, 4, 4" are inserted into the bore 19 through the open end 17 of the housing 1. The open end of the housing is closed off by the tubular casing 11, which terminates in an annular projection 20, having a recess 21, within which is fitted an O-ring seal 22. The exterior face of the annular projection fits snugly against the interior wall of the housing 1, and the O-ring seal provides a fluid-tight coupling between the housing 1 and the casing 11.

The casing 11 has a through bore 13, for flow of pressurized fluid, and inserted in the through bore is a compressed air hose 10, which is threaded onto the hose coupling and held thereon by a spring clip or ring 23. The hose coupling 10' has an air inlet 9, connecting with the interior of the air hose 10 as well as the through passage 8 in the rotor 2. Thus, pressurized fluid can flow through the vibrator via the air hose 10, the air inlet 9, and the passage 8 into the recess in the end piece 12, and thence back along the exterior of the rotor 2 along the threads 3, 5 to the annular space in bore 13, whence it may emerge from the interior of the vibrator.

As is best seen in FIGS. 2 and 3, the threaded portion 5 of the rotor 2 is designed in such a manner that when the crest 25 of a thread 5 on the rotor 2 is against the root 26 of the thread 3 on the housing 1, the diametrically opposed crest 27 of the rotor thread 5 is against the crest 28 of the thread 3 in the housing. The relationship between the diameters of the rotor 2 and the tracks -7, 7', 6, 6' is such that the radially centrifugal force generated during the eccentric rolling motion of the rotor 2 within the housing 1 is absorbed entirely by the tracks.

The operation of the vibrator is as follows:

Compressed air or other pressurizedfluid is supplied through the hose l0 and the air inlet 9 to the interior of the vibrator, passes through the channel 8 in rotor 2 to recess 18, and then along the threaded sections 3, 5 of the housing and rotor. A torque is thus applied to the rotor 2, and the vibration-generating rolling motion of the rotor 2 on the plain portions 6, 6' along the tracks 7, 7' of the housing is thus initiated. Each thread 5 on the rotor 2 forms on a space 30 in conjunction with the corresponding threads 3 in the bushings 4, 4', 4", and this space is pressurized by the pressurized fluid. Owing to the different number of starts of the threads in the rotor and the bushings, this space will move along the narrow of the threaded section as a result of the rolling movement of the rotor. The space thus enclosed has the shape of a spiral loop around the rotor, the length of the loop corresponding to the pitch of the threads. The air passes along the threads, exerting its static pressure upon the rotor, and eventually emerges from the space 30 between the rotor and the housing bushings into the annular exhaust opening in bore 13 of the vibrator.

Having regard to the foregoing disclosures, the following is claimed as the inventive and patentable embodiments thereof:

1. A vibrator adapted to be driven by a pressurized fluid, comprising, in combination, a tubular housing; a cylinder of smaller diameter than the internal diameter of the housing and arranged within the housing; one of the tubular housing and the internal cylinder being rotatable in relation to the other under the influence of the static pressure of pressurized fluid passing through the vibrator, the other beingrelatively stationary, and neither being mechanically driven; the internal cylinder having screw threads on its external periphery, and the tubular housing having screw threads on its internal periphery, the threads of the housing engaging with threads on the internal cylinder, the number of starts in the threads on the housing over a given length being one more than the number of starts of the threads on the internal cylinder over the same length; an inlet and an outlet in the housing, for introduction and withdrawal of a pressurized fluid, and passages connecting the inlet to one side of the threaded portions and connecting the outlet to the other side of the threaded portions, so that pressurized fluid flows operatively along the threads to impart an eccentric and vibrationincluding rolling movement of the internal cylinder within the tubular housing under the influence of the static pressure of the pressurized fluid passing through the vibrator.

2. A vibrator in accordance with claim 1, in which the tubular housing is provided with at least one internal cylindrical bushing, on the internal periphery of which are disposed the threads engaging with the threads on the internal cylinder.

3. A vibrator in accordance with claim 2, having a plurality of separate cylindrical bushings, arranged axially in relation to each other, and within which the internal cylinder is disposed.

4. A vibrator in accordance with cliam 2, in which the minimum length of the bushings is equal to at least one pitch of the threads along the internal periphery thereof. I

5. A vibrator in accordance with claim 2, in which the internal cylinder is provided with a plain cylindrical section at each end, and the tubular housing is provided with internal tracks positioned opposite the plain cylindrical section, and on which the internal cylinder rolls via the plain cylindrical section, the centrifugal force generated by the eccentric rolling movement of the internal cylinder being taken up by the tracks.

6. A vibrator according to claim 5 in which the outside diameter of the bushings is equal to the inside diameter of the tubular housing, and the larger inside diameter is one height of thread larger than the outside diameter of the internal cylinder.

7. A vibrator in accordance with claim 1, adapted to be driven by compressed air.

8. A vibrator in accordance with claim I, in which the tubular housing has a flat cap at one end, adapting it for the compaction of concrete.

9. A vibrator in accordance with claim I, in which the tubular housing has one open end, in which is inserted an end piece including a line for provision of pressurized fluid to the vibrator, and an annular outlet for exhaust of pressurized fluid from the vibrator.

10. A vibrator in accordance with claim 9, in which the internal cylinder has an internal passage connecting with the inlet for pressurized fluid and opening onto one end of the threaded portion of the cylinders, and the annular outlet opens onto the other end of the threaded portion of the cylinders, for fluid flow of pressurized fluid from the inlet to the outlet along the threaded portion.

UNITED STATES PATENT OFFICE CERTIFICATE OF- CORRECTION Patent No. 3,746,310 Dated July 17, 1973 lnventofls) .jJvohnny Fransson et a1 It is certified that error appears inthe above-identified patent and that said Letters Patent are hereby corrected as vshown below:

On the coiTer' sheet "[73] Assignee: A BYVibra-Verken, Solna, Sweden?" should read [73] Assignee: A Vibro-Verken, Solna, Sweden Column 4, 1ine'l6, cancel "over a given length"; line- 18,; cance1 "over the same length"; line 36,

"cliam" should read claim Signed and sealed this 20th day of August 1974.

(SEAL) Attest: R

MCCOY M. GIBSON, JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050(10-69) USCOMM-DC 60376-P89 u.s. covenant": rumrms OFFICE: I9" 0-356-32". 

1. A vibrator adapted to be driven by a pressurized fluid, comprising, in combination, a tubular housing; a cylinder of smaller diameter than the internal diameter of the housing and arranged within the housing; one of the tubular housing and the internal cylinder being rotatable in relation to the other under the influence of the static pressure of pressurized fluid passing through the vibrator, the other being relatively stationary, and neither being mechanicallY driven; the internal cylinder having screw threads on its external periphery, and the tubular housing having screw threads on its internal periphery, the threads of the housing engaging with threads on the internal cylinder, the number of starts in the threads on the housing over a given length being one more than the number of starts of the threads on the internal cylinder over the same length; an inlet and an outlet in the housing, for introduction and withdrawal of a pressurized fluid, and passages connecting the inlet to one side of the threaded portions and connecting the outlet to the other side of the threaded portions, so that pressurized fluid flows operatively along the threads to impart an eccentric and vibration-including rolling movement of the internal cylinder within the tubular housing under the influence of the static pressure of the pressurized fluid passing through the vibrator.
 2. A vibrator in accordance with claim 1, in which the tubular housing is provided with at least one internal cylindrical bushing, on the internal periphery of which are disposed the threads engaging with the threads on the internal cylinder.
 3. A vibrator in accordance with claim 2, having a plurality of separate cylindrical bushings, arranged axially in relation to each other, and within which the internal cylinder is disposed.
 4. A vibrator in accordance with cliam 2, in which the minimum length of the bushings is equal to at least one pitch of the threads along the internal periphery thereof.
 5. A vibrator in accordance with claim 2, in which the internal cylinder is provided with a plain cylindrical section at each end, and the tubular housing is provided with internal tracks positioned opposite the plain cylindrical section, and on which the internal cylinder rolls via the plain cylindrical section, the centrifugal force generated by the eccentric rolling movement of the internal cylinder being taken up by the tracks.
 6. A vibrator according to claim 5 in which the outside diameter of the bushings is equal to the inside diameter of the tubular housing, and the larger inside diameter is one height of thread larger than the outside diameter of the internal cylinder.
 7. A vibrator in accordance with claim 1, adapted to be driven by compressed air.
 8. A vibrator in accordance with claim 1, in which the tubular housing has a flat cap at one end, adapting it for the compaction of concrete.
 9. A vibrator in accordance with claim 1, in which the tubular housing has one open end, in which is inserted an end piece including a line for provision of pressurized fluid to the vibrator, and an annular outlet for exhaust of pressurized fluid from the vibrator.
 10. A vibrator in accordance with claim 9, in which the internal cylinder has an internal passage connecting with the inlet for pressurized fluid and opening onto one end of the threaded portion of the cylinders, and the annular outlet opens onto the other end of the threaded portion of the cylinders, for fluid flow of pressurized fluid from the inlet to the outlet along the threaded portion. 